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MediaPipe Selfie Segmentation

Table of contents
  1. Overview
  2. Models
  3. ML Pipeline
  4. Solution APIs
    1. Cross-platform Configuration Options
      1. model_selection
    2. Output
      1. segmentation_mask
    3. Python Solution API
    4. JavaScript Solution API
  5. Example Apps
    1. Mobile
    2. Desktop
  6. Resources

Overview

Fig 1. Example of MediaPipe Selfie Segmentation.

MediaPipe Selfie Segmentation segments the prominent humans in the scene. It can run in real-time on both smartphones and laptops. The intended use cases include selfie effects and video conferencing, where the person is close (< 2m) to the camera.

Models

In this solution, we provide two models: general and landscape. Both models are based on MobileNetV3, with modifications to make them more efficient. The general model operates on a 256x256x3 (HWC) tensor, and outputs a 256x256x1 tensor representing the segmentation mask. The landscape model is similar to the general model, but operates on a 144x256x3 (HWC) tensor. It has fewer FLOPs than the general model, and therefore, runs faster. Note that MediaPipe Selfie Segmentation automatically resizes the input image to the desired tensor dimension before feeding it into the ML models.

The general model is also powering ML Kit, and a variant of the landscape model is powering Google Meet. Please find more detail about the models in the model card.

ML Pipeline

The pipeline is implemented as a MediaPipe graph that uses a selfie segmentation subgraph from the selfie segmentation module.

Note: To visualize a graph, copy the graph and paste it into MediaPipe Visualizer. For more information on how to visualize its associated subgraphs, please see visualizer documentation.

Solution APIs

Cross-platform Configuration Options

Naming style and availability may differ slightly across platforms/languages.

model_selection

An integer index 0 or 1. Use 0 to select the general model, and 1 to select the landscape model (see details in Models). Default to 0 if not specified.

Output

Naming style may differ slightly across platforms/languages.

segmentation_mask

The output segmentation mask, which has the same dimension as the input image.

Python Solution API

Please first follow general instructions to install MediaPipe Python package, then learn more in the companion Python Colab and the usage example below.

Supported configuration options:

import cv2
import mediapipe as mp
mp_drawing = mp.solutions.drawing_utils
mp_selfie_segmentation = mp.solutions.selfie_segmentation

# For static images:
IMAGE_FILES = []
BG_COLOR = (192, 192, 192) # gray
MASK_COLOR = (255, 255, 255) # white
with mp_selfie_segmentation.SelfieSegmentation(
    model_selection=0) as selfie_segmentation:
  for idx, file in enumerate(IMAGE_FILES):
    image = cv2.imread(file)
    image_height, image_width, _ = image.shape
    # Convert the BGR image to RGB before processing.
    results = selfie_segmentation.process(cv2.cvtColor(image, cv2.COLOR_BGR2RGB))

    # Draw selfie segmentation on the background image.
    # To improve segmentation around boundaries, consider applying a joint
    # bilateral filter to "results.segmentation_mask" with "image".
    condition = np.stack((results.segmentation_mask,) * 3, axis=-1) > 0.1
    # Generate solid color images for showing the output selfie segmentation mask.
    fg_image = np.zeros(image.shape, dtype=np.uint8)
    fg_image[:] = MASK_COLOR
    bg_image = np.zeros(image.shape, dtype=np.uint8)
    bg_image[:] = BG_COLOR
    output_image = np.where(condition, fg_image, bg_image)
    cv2.imwrite('/tmp/selfie_segmentation_output' + str(idx) + '.png', output_image)

# For webcam input:
BG_COLOR = (192, 192, 192) # gray
cap = cv2.VideoCapture(0)
with mp_selfie_segmentation.SelfieSegmentation(
    model_selection=1) as selfie_segmentation:
  bg_image = None
  while cap.isOpened():
    success, image = cap.read()
    if not success:
      print("Ignoring empty camera frame.")
      # If loading a video, use 'break' instead of 'continue'.
      continue

    # Flip the image horizontally for a later selfie-view display, and convert
    # the BGR image to RGB.
    image = cv2.cvtColor(cv2.flip(image, 1), cv2.COLOR_BGR2RGB)
    # To improve performance, optionally mark the image as not writeable to
    # pass by reference.
    image.flags.writeable = False
    results = selfie_segmentation.process(image)

    image.flags.writeable = True
    image = cv2.cvtColor(image, cv2.COLOR_RGB2BGR)

    # Draw selfie segmentation on the background image.
    # To improve segmentation around boundaries, consider applying a joint
    # bilateral filter to "results.segmentation_mask" with "image".
    condition = np.stack(
      (results.segmentation_mask,) * 3, axis=-1) > 0.1
    # The background can be customized.
    #   a) Load an image (with the same width and height of the input image) to
    #      be the background, e.g., bg_image = cv2.imread('/path/to/image/file')
    #   b) Blur the input image by applying image filtering, e.g.,
    #      bg_image = cv2.GaussianBlur(image,(55,55),0)
    if bg_image is None:
      bg_image = np.zeros(image.shape, dtype=np.uint8)
      bg_image[:] = BG_COLOR
    output_image = np.where(condition, image, bg_image)

    cv2.imshow('MediaPipe Selfie Segmentation', output_image)
    if cv2.waitKey(5) & 0xFF == 27:
      break
cap.release()

JavaScript Solution API

Please first see general introduction on MediaPipe in JavaScript, then learn more in the companion web demo and the following usage example.

Supported configuration options:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <script src="https://cdn.jsdelivr.net/npm/@mediapipe/camera_utils/camera_utils.js" crossorigin="anonymous"></script>
  <script src="https://cdn.jsdelivr.net/npm/@mediapipe/control_utils/control_utils.js" crossorigin="anonymous"></script>
  <script src="https://cdn.jsdelivr.net/npm/@mediapipe/drawing_utils/drawing_utils.js" crossorigin="anonymous"></script>
  <script src="https://cdn.jsdelivr.net/npm/@mediapipe/selfie_segmentation/selfie_segmentation.js" crossorigin="anonymous"></script>
</head>

<body>
  <div class="container">
    <video class="input_video"></video>
    <canvas class="output_canvas" width="1280px" height="720px"></canvas>
  </div>
</body>
</html>
<script type="module">
const videoElement = document.getElementsByClassName('input_video')[0];
const canvasElement = document.getElementsByClassName('output_canvas')[0];
const canvasCtx = canvasElement.getContext('2d');

function onResults(results) {
  canvasCtx.save();
  canvasCtx.clearRect(0, 0, canvasElement.width, canvasElement.height);
  canvasCtx.drawImage(results.segmentationMask, 0, 0,
                      canvasElement.width, canvasElement.height);

  // Only overwrite existing pixels.
  canvasCtx.globalCompositeOperation = 'source-in';
  canvasCtx.fillStyle = '#00FF00';
  canvasCtx.fillRect(0, 0, canvasElement.width, canvasElement.height);

  // Only overwrite missing pixels.
  canvasCtx.globalCompositeOperation = 'destination-atop';
  canvasCtx.drawImage(
      results.image, 0, 0, canvasElement.width, canvasElement.height);

  canvasCtx.restore();
}

const selfieSegmentation = new SelfieSegmentation({locateFile: (file) => {
  return `https://cdn.jsdelivr.net/npm/@mediapipe/selfie_segmentation/${file}`;
}});
selfieSegmentation.setOptions({
  modelSelection: 1,
});
selfieSegmentation.onResults(onResults);

const camera = new Camera(videoElement, {
  onFrame: async () => {
    await selfieSegmentation.send({image: videoElement});
  },
  width: 1280,
  height: 720
});
camera.start();
</script>

Example Apps

Please first see general instructions for Android, iOS, and desktop on how to build MediaPipe examples.

Note: To visualize a graph, copy the graph and paste it into MediaPipe Visualizer. For more information on how to visualize its associated subgraphs, please see visualizer documentation.

Mobile

Desktop

Please first see general instructions for desktop on how to build MediaPipe examples.

Resources